The present invention relates to intrusion alarms and, more particularly, to a method and apparatus which relies on the detection of an auditory cry of alarm of an animal to operate an intrusion reaction device.
Throughout recorded history, men have relied upon the superior olfactory and auditory senses of other animals to give them warning of the approach of danger or an intruder. In primitive societies, the cries of alarm of various birds and other animals are carefully learned by men for their value in detecting the presence of danger.
Even in industrialized societies, watchdogs are commonly kept for the purposes of giving an alarm and for frightening away would-be intruders. Such watchdogs have highly refined sensory mechanisms, including senses of hearing and smell far superior to those possessed by human beings. Watchdogs also have an ability to distinguish between known and unknown persons and, some believe, to discern friendly or hostile intentions from the actions or demeanor of unknown persons.
Thus the watchdog is, in some ways, ideally suited as an indicator of hostile intrusion or intended burglary. No electronic detector yet devised can match either the sensitivity or the discriminatory ability of a watchdog in defending against hostile intrusions.
There are, nevertheless, situations in which the barking of a watchdog is an inadequate warning, and an inadequate deterrent to hostile intrusions. For example, if the watchdog is kept in a remote building or kennel located some distance from a main dwelling, his barking may not be adequate to awaken sleeping residents. Also, if the dog is confined, his barking may not deter a would-be intruder from entering into a protected area, for example.
Accordingly, some auxiliary means of sensing the barking of a watchdog or, indeed, the cry of alarm of any animal kept on premises, is desirable. Such an auxiliary means might be used to provide a remote indication of intrusion or might be used to operate a defensive mechanism by, for example, turning on floodlights or electrically locking doors or gates.